The most interesting of our Interaction Device developments may well be this
simple ring like IR device that enables direct pointing. By direct
pointing we mean that the device continually returns the position in a plane
(normally a display screen) that your finger is pointing at - the most
natural pointing technique we can think of.
The device is described in US Patent # 6,184,863. A more reader friendly
description is in our UIST97 paper
If you want to see the device in action, you can look at this (6.7mb) Quicktime video
or the higher resolution (12mb) version.
You may need to update your Quicktime